The victim died in a convenience store in north Houston just after 10pm Monday night. He had only been on the job just a couple of hours. Police believe the killers cased out the store before the murder and the clerk spoke to one of his killers just an hour before his death.

Almost 24 hours after the deadly robbery, the Siesta Food Mart on Aldine-Bender and Cotillion is closed. The owner is looking for someone to run the store. The last man who did, a fill-in for Luis Garcia who had just been fired, ended up dead.

"I'm supposed to be dead right now," said Garcia.

Surveillance cameras captured the killing just after 10pm Monday night. The store clerk, Joe Fernandes, 54, was shot to death, Houston police believe, because he didn't act fast enough for the masked gunmen. However, they don't want you to focus on that, rather on a customer who bought cookies and water about an hour earlier.

The video first shows a gold or tan sedan driving slowly. A man enters the store, grabs some snacks and pays Fernandes who's behind the counter. An hour later, three armed men sneak in and at gunpoint demand cash. Within 45 seconds, Fernandes is dead, the gunmen are off and police need the public's help.

"We've been working murders, robberies for a very long time. I don't think I've seen guys like this. They certainly looked like professionals, knew what they were doing and were fully intent on completing the task at hand," said Officer Miller.

Since the robbers are covered head-to-toe, police are zeroing in on the guy who scouted the store. Finding him, they believe, is key to preventing other violent robberies and key to easing some pain.

"They are rattled to the core," said Officer Miller.

Fernandes' 23-year-old son was also brutally murdered a year ago. He was shot and set on fire allegedly by his roommate at their Missouri City apartment. The family's neighbor, Sarah Siddiqui, can't imagine what his mother must be going through.

"She couldn't get over it. She was just trying to fix herself over the first death and now her husband," said Siddiqui.

Houston detectives say the three men got away in an older model gold or tan four-door vehicle parked on the 15,900 block of Cotillion. They were last seen driving southbound.

Police ask anyone with information about this crime to call Crime Stoppers at 713-222-TIPS or log on to Crime-Stoppers.org. There is a cash reward, and you can remain anonymous.